Filtering system for the protection against biological agents

ABSTRACT

The invention refers to a filtering system composed by a face mask and a filter against biological agents, joined together by a new connector. The connector joins the filter to the mask in an easy, fast and affective way. The filtering system provides a very high barrier against biological agents, a high seal and is very easy to use.

FIELD OF THE INVENTION

The present invention refers to a filtering system composed by a facemask and a filter against biological agents, joined together by a newconnector.

PRIOR ART

There are several situation where workers are exposed to infectivebiological agents, that is micro-organisms, including those which havebeen genetically modified, which may be able to provoke infection,allergy or toxicity.

In some work situations, e.g. microbiological laboratories andbiotechnological productions the infective agents are usually wellknown.

In other types of work, the agents the workers are exposed may not beknown and only possible risks can be assessed; this happens, forexample, in agriculture work, waste treatment, in particular hospitalwaste, veterinary laboratories, emergency clean-up.

In all these circustances, the use of protective means is strictlynecessary. In particular, protection masks are widely used in anysituation in which it is necessary to guarantee the user's protectionfrom the viral trasmission by air.

Several kind of protective masks have been described, for example in EP0459123 B1 (priority DE 4017336), EP 0511592 A1 (priority IT MI911172),EP 0511593 B2 (priority IT MI911171) and IT 1045644.

These masks ensure the user's protection from gases, powders and againstchemical agents.

In many activities is required the protection against biological agents,for example in hospital and veterinary environments.

For example, the protection against biological agents is important inanaesthetic systems which can be easily contaminated by bacteria therebyincreasing the risk of transmission to subsequent patients.

There are several studies on the problem of cross infection byanaesthetic breathing systems (see, for example, “Circuiti per anestesiae infezione crociata” —D. T. M. Leijten, R. P. Mouton, V. S.Rejger-Incontro di aagiornamento A.A.R.O.I.—Arezzo 1991).

In order to protect the anaesthetic system from contamination as well asthe patient from the contaminated apparatus, the most efficient way isthe air filtration.

Filters for this aim are described, for example, in “Bacteria Removal ofthe Pall Ultipor Breathing System Filtei”—M. J. Latham Ph. D.,Scientific and Laboratory Services, Pall Europe Limited.

In other situations aqualungs are used as protective devices againstbiological agents.

Aqualungs have a very high efficiency but show some disadvantages, owingto their dimensions with relevant hindrance and troubles inuncomfortable situations like in emergengy works.

Consequently, there was the need of finding a filtering system which,besides ensuring an effective barrier against biological agents, waseasy and comfortable for using in any situation.

SUMMARY

The present invention refers to a filtering system composed by a facemask and a filter against biological agents, joined together by a newconnector.

The filtering system has high barrier properties against biologicalagents, high seal and is very easy to use.

DESCRIPTION OF THE INVENTION

The new filtering system consists of

-   A) a protection face mask-   B) a filter against biological agents-   C) a connector useful to easily, quickly and efficaciously join the    filter to the mask.

FIGS. 1 and 2 represent, respectively, the front and side view of thefiltering system.

In FIG. 2, the filter is indicated by letter B while the connector ismarked by letter C.

The mask is a protective mask complying with the existing rules, inparticular with EN 136:98, class 3, and Directive 89/686/CEE andsubsequent modifications.

The mask comprises a plastic face-piece, tipically a butylic rubber orsilicone face-piese, a transparent plastic screen, for example apolycarbonate screen, capable of permitting the user's vision and aplastic group containing the breathing means, to put the inner part ofthe mask into communication with filters or acqualung, the expirationvalves, the inspiration valves and the phonic means.

The face-piece is provided with a sealing lip arranged to act inabutment on the user's face and two valves providing the air circulationto prevent the screen from tarnishing.

The mask is equipped with buckles for fast and easy fastening.

The mask is equipped with a sleeve having standard threadings, usablewith all the breathing systems equipped with EN 148-1-DIN 3183connector, which allows the use of typical filters against gases,powders and chemicals, the use of oxygen closed-circuit breathingapparatus as well as the use in overpressure conditions.

The filter for the protection against biological agents is a single-usefilter consisting in a pleated membrane made of ceramic microfibers,with high efficiency as barrier against bacteriae and viruses.

The filter is put inside a transparent plastic container, for example apolypropylene, butadiene-styrene or EVA-polycarbonate copolymercontainer, having controlled seal and blunted corners.

FIGS. 3 and 4 represent the filter with the relevant dimensions in mm.

Furthermore the position of the membrane inside the filter is alsoshown. The membrane is hydrophobic (liquid-tigth) on the worker side,avoiding the penetration of liquids with surface tension>70 dine/cm, andis hydrophilic on the environment side, in order to ensure an highhumidification yield.

The moisture resistance, at 60 l/min, is <2.5 cm H₂O and the loose ofmoisture in the expiration phase is less than 8 mg/l.

The filter also provides an high heat recovery from the gases during theinspiratory phase.

The filtering area is 700 cm² while the overall exchange surface is morethan 10 m².

The weigth of the filter ranges between 44 and 50 g. and the volumeranges between 80 and 90 ml.

The filter described as above and used in the filtering apparatus of thepresent invention, is a known system widely used in the sanitary fieldin the breathing circuits in order to provide a total barrier to thepenetration of viruses and bacteria which can be transmitted by gasesand liquids, such as contaminated body fluids.

It is consequently equipped with connectors for the use in standardsanitary apparatus, for example with connector 22/15 MAF complying withthe standard ISO 5356-1 and 5356-2.

In addition, the connector for Luer-lock monitoring, complying with thestandard ISO 594-2, can also be mounted.

The filter was not constructed and never applied for the use incombination with protection devices such as face masks.

The connector (FIG. 5 and 6) consists in a cylinder having, on the maskside, external diameter equal to 40 mm and the appropriate threading toscrew it on the mask.

The external diameter of the filter side is 35.5 mm while the internaldiameter is 25.6 (+0.2/−0.0) mm.

The cylinder is made of plastic material, in particular of apolyacetalic copolymer containing glass fibers.

The inside wall of the connector has a circular drill, at a 5 mmdistance from the edge (filter side), 4 mm wide and 2.4 mm deep, inwhich an O-ring is inserted with blocking and sealing function.

The ring can be produced with different mixtures, for example withfluoro, silicone, ethylene-propylene or nitrile based mixtures,preferably with nitrilic mixture.

The connector can be applied on the mask by screwing and, on its turn,ensures the fast and easy application of the filter by simple pressure.

The filter can also be previously assembled with the connector in orderto allow a faster application to the face mask; in this case the O-ringis not necessary and the assemblage can be achieved by knowntechnologies as, for example, the use of suitable glues.

The system, thanks to the combination of the barrier properties of thefilter with the tigth seal of the mask and the connectors, provides anefficient protection against the biological agents.

The efficacy of the pleated filter as a barrier to bacteriae and viruseshave been widely investigated by tests with microorganisms containingaerosols and with liquids contaminated by bacteriae and viruses.

In particular, the filter turned out to be effective in preventingcontamination with Hepatitis C Virus (HCV), Hepatitis B Virus (HBV),Human Immunodeficiency Viruses (HIV), Sp. Pseudomonas, Staphylococcusaureus, Serratia Marcescescens, Mycobacterium Tuberculosis and Virus MS2(bacteriophage).

The details of the main known tests can be found in the followingpublications:

-   -   “efficacy of a pleated hydrophobic filter as a barrier to        Hepatitis C transmission within breathing systems” (G. Lioyd, J.        Howells, J. Benbough—Centre for Applied Microbiology & Research—        Porton Down, Salisbury, Wiltshire SP4 OJG, UK);    -   “efficacy of a pleated hydrophobic filter as a barrier to human        immunodeficiency virus transmission within breathing systems”        (G. Lioyd, J. Howells—Centre for Applied Microbiology &        Research—Porton Down, Salisbury, Wiltshire SP4 OJG, UK);    -   “efficacia di un filtro idrofobico con membrana pieghettata        quale barriera alla trasmissione del Mycobacterium Tuberculosis        nei sistemi di ventilazione artificiale” (S. Speigth, A. M.        Bennet, M. R. Lever, J. Benbough—Centre for Applied Microbiology        & Research—Porton Down, Salisbury, Wiltshire SP4 OJG, UK).

In all the above tests the filter efficiency turned out to be superiorto 99.9999%.

In addition, the barrier efficacy of the filter has been demonstratedwith an aerosol of monodispersed bacteriophage MS-2 (Viral removalefficiency of the Pall Ultipor Breathing System filter—P. R. Ball, D.Saunders—Bsc. Scientific and Laboratory services Pall Europe Limited).

MS-2 is a polyhedric virus with approximate dimension 0.02 microns,which is not pathogenic to humans and serves to simulate viruses, withsimilar shape and dimensions, that are pathogenic to humans.

Also in this case, the efficiency of the filter turned out to besuperior to 99.999%.

It is worth mentioning that the test was carried out with monodispersedparticles, that represents the most critical situation, in normalconditions the majority of microorganisms are not monodispersed but, onthe contrary, they are in a wide variety of drop forms and of singlemicroorganisms, so that the efficiency in normal condition of use may beeven superior to the tests' results.

Consequently the filter is effective against any microorganism withdimension larger than MS-2 bacteriophage, in particular against theBacillus Anthracis.

The connector has a very high seal ensuring a safe airtigth during theuse of the filtering system,

The face-piece is provided with a sealing lip arranged to act inabutment on the user's face and to adapt to any face shape; this ensuresa perfect and safe seal.

The overall system's seal has been assessed by a pneumatic test carriedout via a mask-proof apparatus.

The system of the present invention is handy and comfortable thanks toits ligthtness and to its easy use, thanks to the simple way to put iton and, finally, thanks to the rapid way of application and removal ofthe filter from the mask.

The mask can be put on through the following procedure:

-   -   the filter is joined to the mask via the connector, then the        mask is tigthtly fastened by means of the straps to the user's        face.

The system, besides ensuring an easy use and high comfort, alsoguarantees the maximum visual field with complete absence of opticaldistorsions.

1. A filtering system consisting of: A) a protective face mask B) afilter against biological agents C) a connector useful to easily,quickly and efficaciously join the filter to the mask.
 2. A filteringsystem as claimed in claim 1 characterized in that said mask comprises aplastic face-piece, a transparent plastic screen, a plastic groupcontaining the breathing means, to put the inner part of the mask intocommunication with filters or aqualungs, the expiration valves, theinspiration valves and the phonic means and, finally, a sealing lip andtwo valves for air circulation.
 3. A filtering system as claimed inclaim 2, characterized in that the plastic face-piece is made of butylicrubber or silicone, the screen is manufactured by polycarbonate and thesealing lip is made of natural rubber.
 4. A filtering system as claimedin claim 1 characterized in that it is equipped with buckles for quickfastening.
 5. A filtering system as claimed in claim 1, characterized inthat it is equipped with a sleeve having threadings usable with all thebreathing systems provided with EN 148-1 DIN 3183 connector.
 6. Afiltering system as claimed in claim 1 characterized in that the filteris a protective filter against biological agents consisting in a pleatedmembrane made of ceramic microfibers.
 7. A filtering system as claimedin claim 6, wherein said membrane is hydrophobic on the worker side,avoiding the penetration of liquid with surface tension>70 dine/cm, andis hydrophilic on the environment side, in order to ensure an highhumidification yield.
 8. A filtering system as claimed in claim 6wherein said membrane is put inside a transparent plastic container,having controlled seal and blunted corners.
 9. A filtering system asclaimed in claim 8, wherein the plastic material of the container ismade of polypropylene, butadiene-styrene or EVA polycarbonatetecopolymer.
 10. A filtering system as claimed in claim 1 characterized inthat the connector consists in a cylinder having, on the mask side,external diameter equal to 40 mm and the appropriate threading to screwit on the mask; the external diameter of the filter side is 35.5 mmwhile the internal diameter is 25.6 (+0.2/−0.0) mm.
 11. A filteringsystem as claimed in claim 10 characterized in that the inside wall ofthe connector has a circular drill, at 5 mm distance from the edge(filter side), 4 mm wide and 2.4 mm deep, in which an O-ring is insertedwith blocking and sealing function.
 12. A filtering system as claimed inclaim 10 characterized in that the cylinder is made of plastic material.13. A filtering system as claimed in claim 12 wherein the said plasticmaterial of the cylinder is a polyacetalic copolymer containing glassfibers.
 14. A filtering system as claimed in claim 11 characterized inthat the O-ring is manufactured by a fluoro or silicone orethylene-propylene or nitrile based mixture.
 15. A method providingprotection against biological agents, comprising securing to a user thefiltering system of claim.
 16. The method of claim 15, wherein saidbiological agents are at least one selected from the group consisting ofHepatitis C Virus (HCV), Hepatitis B Virus (HBV), Human ImmunodeficiencyViruses (HIV), Sp. Pseudomonas, Staphylococcus aureus, SerratiaMarcescescens and Mycobacterium Tuberculosis.
 17. The method of claim15, wherein said biological agents is the Bacillus Anthracis.
 18. Aconnector as claimed in claim 10 useful to connect a protective maskwith a filter against biological agents.
 19. A filtering systemcomprising: a mask comprising a plastic face-piece, a transparentplastic screen, a plastic group containing a breathing means, to put theinner part of the mask into communication with filters or aqualungs,expiration valves, inspiration valves and phonic means and, finally, asealing lip and two valves for air circulation; a filter that is aprotective filter against biological agents consisting in a pleatedmembrane made of ceramic microfibers; and a connector comprising acylinder having, on the mask side, external diameter equal to 40 mm andthe appropriate threading to screw it on the mask; the external diameterof the filter side being 35.5 mm while the internal diameter is 25.6(+0.2/−0.0) mm.